The present invention relates generally to mass storage or tape library systems and, in particular, to a self contained, easily installed apparatus and method for transferring tape cartridges between distinct tape library systems to increase the storage capacity of an overall mass storage system.
There are a variety of xe2x80x9cmass storagexe2x80x9d or xe2x80x9ctape libraryxe2x80x9d systems, consisting generally of one or more recording/reproducing tape drives, a number of tape cartridges stored in bins, and a robotics assembly for transferring cartridges to and from the tape drives and the cartridge bins.
Most of the typical mass storage or library systems are not xe2x80x9cexpandablexe2x80x9d, in that additional cartridges beyond their local storage capacity of cartridge bins must be inserted and removed manually. Those systems which offer expandability with some form of xe2x80x9cpass-throughxe2x80x9d or conveyor system are generally slow, difficult to access for maintenance, or are suitable only for very large data-warehousing applications.
Accordingly, there is a need for a simple self contained means of mechanically transferring cartridges between adjacent distinct library systems to increase overall mass storage system capacity, and one which can be easily installed and expanded in an installation at a customer""s site.
The present invention overcomes the above-mentioned disadvantages of the typical tape library expanding apparatus while providing a relatively simple and easily installed transfer unit employing a movable cartridge bin assembly which travels horizontally between two or more cabinets of respective tape library systems. The movable bin assembly is presented to a typical cartridge handling robot of respective library systems as if it were part of the stationary bin structure housed within the associated cabinet.
To this end, the transfer unit of the present invention is configured to work in conjunction with, for example, from two to four library systems generally contained in 24-inch rack cabinets, such as the DST-712 library system manufactured by Ampex Corporation, Redwood City, Calif., or with, for example, one, two or more DST-712 library systems and a DST-812 library system also manufactured by Ampex Corporation.
More particularly, the transfer unit includes a support means such as a base channel which extends into for example two adjacent library systems, or through a third or fourth library system in a three or four library system configuration. A movable bin assembly is translatably supported by the base channel and is bidirectionally moved rapidly between the library systems. The bin assembly is stopped accurately and repeatedly at preset locations, herein termed xe2x80x9cdepotsxe2x80x9d, where there is one depot within each cabinet of the library systems for a respective transfer unit. A drive means, consisting of, for example, a motor driven cable drum and an elongated cable wrapped about the cable drum, secured to the bin assembly and extending the length of the support means, causes the rapid and accurate movement of the bin assembly between a depot in each respective library system. The depot locations are xe2x80x9clearnedxe2x80x9d by each cartridge handling robot of the library systems as if they were permanent addresses within their respective stationary bin arrays. Optical sensors associated with each depot accurately locate each depot and thus the respective bin assembly stop location. An optical sensor also determines whether a cartridge is present in the bin assembly at any of the depots.
As may be seen, the present invention provides for the retrieval and loading of a cartridge in a constant orientation, that is, without need to rotate the cartridge.
An alternative embodiment of the present invention employs a dual cartridge bin assembly which enables the transfer unit of the invention to receive a cartridge from the robot, at the same time that the transfer unit delivers a cartridge to that same robot for storage or delivery to the tape drive unit.